Several studies have observed that stocks tend to drop by an amount that is less than the dividend on the ex-dividend day, the so-called ex-dividend day anomaly. However, there still remains a lack of consensus for a single explanation of this anomaly. Different from other studies, this dissertation attempts to answer the primary research question: How can investors make trading profits from the ex-dividend day anomaly and how much can they earn? With this goal, I examine the economic motivations of equity investors through four main hypotheses identified in the anomaly’s literature: the tax differential hypothesis, the short-term trading hypothesis, the tick size hypothesis, and the leverage hypothesis. While the U.S. ex-dividend anomaly is well studied, I examine a long data window (1975 to 2010) of Thailand data. The unique structure of the Thai stock market allows me to assess all four main hypotheses proposed in the literature simultaneously. Although I extract the sample data from two data sources, I demonstrate that the combined data are consistently sampled. I further construct three trading strategies: “daily return,” “lag one daily return,” and “weekly return” to alleviate the potential effect of irregular data observation. I find that the ex-dividend day anomaly exists in Thailand, is governed by the tax differential and is driven by short-term trading activities. That is, investors trade heavily around the ex-dividend day to reap the benefits of the tax differential. I find mixed results for the predictions of the tick size hypothesis and results that are inconsistent with the predictions of the leverage hypothesis. I conclude that, on the Stock Exchange of Thailand, juristic and foreign investors can profitably buy stocks cum-dividend and sell them ex-dividend while local investors should engage in short sale transactions. On average, investors who employ the daily return strategy have earned significant abnormal return up to 0.15% (45.66% annualized rate) and up to 0.17% (50.99% annualized rate) for the lag one daily return strategy. Investors can also make a trading profit by conducting the weekly return strategy and earn up to 0.59% (35.67% annualized rate), on average.

在過去的理論中，自從Campbell與Beranek 在1955年之研究發現除息之行 為會影響投資者的組合決策之後，除息及除權行為就成為其它學者深入探 所的一重要課題。如Miller與Modigliani (1961)提出的顧客效果假說， Elton 與 Gruber(1970) 提出稅率誘發的顧客效果，認為可從除息（權） 日的價格找出投資人的邊際稅率。但是學者Kalay(1984) 認為一般來說， 公司在進行除息或除權時，股價之下降通常不會等於息值或權值，對某些 投資人而言在除息（權）日可能存有一些套利的機會，故其另外提出所謂 的短線交易假說來分析除息（權）日的交易行為，而 Lakon- ishok和 Vermaelen(1986)則進一步從除息日前後有異常交易量證實短線交易的存 在。本研究即是從除息（權）日前後之交易來分析是否存有短線交易的行 為；並透過政府在民國78年對證券交易所得稅的課徵對投資人交易行為的 影響，提供政府未來開徵證券交易所得稅之參考。最後亦從交易成本與股 利收益率來分析對短線交易的影響。所得到結果如下： 1.在78年時，除 息日前後交易量呈現減少的情況，而在79至82年交易量則有異常增加的現 象。顯示投資人在78年並未透過除息事件來減少其稅負，即證券交易所得 稅的開徵對投資人的交易行為是無影響的；而在79至82年投資人的確有在 除息日前後採取節稅之短線交易。 2.如果將交易依照成股利收益率大小 予與分群，本研究發現異常交易量將隨著股利收益率的增加而增加；而驗 證股利收益率較高的股票對短線交易者的吸引力是較大的。 3.如果以交 易成本去分析其對除息日交易的影響，本研究採用交易群體為交易成本之 替代變數，發現交易成本相對投資報酬來講是很小的，故投資人在從事短 線交易時並不會考慮到其交易成本。

Abstract   Background: The dividend ex-day effect is the tendency of the stock price drop on the ex-day to be less than the dividend per share. This inclination is contrary to established theory of rational investor behaviour and is, thus, considered an anomaly in capital markets. The phenomenon was first observed more than half a century ago and has puzzled researchers ever since, resulting a myriad of theories trying to explain its cause. Nevertheless, the dividend ex-day effect still stands without a conclusive explanation. In Sweden, few studies have been conducted and none succeeds in explaining the phenomenon. In a recent addition to the many explanatory theories, Efthymiou and Leledakis (2014) propose the disposition effect as the driving factor behind the dividend ex-day effect. Compelling evidence for this notion is provided in an empirical study of the US market, warranting the consideration of a similar investigation in the Swedish market.   Purpose: The purpose of this study is to examine the relationship between the dividend ex-day effect and the disposition effect in the Swedish stock market. Method: This study is conducted using a deductive approach and a quantitative research strategy. Secondary data of OMXS stocks during the 2013-2017 period is gathered from Thomson Reuters Datastream. To fulfil the purpose, one sample t-tests and regression analyses are performed. Conclusion: Statistically significant results confirm that there is a pervasive dividend ex-day effect on the OMXS market. From here, it is found that there is a substantial difference in the price drop between stocks based on their performance: winning stocks display a higher price drop on the ex-day compared to losing stocks. Regression analyses indicate a positive relationship between the dividend ex-day effect and the disposition effect. Some evidence, although not statistically significant, suggest that for a specific stock, the price drop will be greater in times when the stock has had positive returns compared to when it has had negative returns. A remarkable finding in this study is that all tests indicate that the positive relationship between the dividend ex-day effect and the disposition effect appears to be fading out as the holding period of stocks gets longer.

Denna studies syfte är att testa om det finns ett statistiskt samband mellan det nominella aktiepriset och ex-dagseffekten på Nasdaq OMX Stockholm. Ett tydligt samband skulle därmed vara ett ytterligare motiv till företagens beslut om genomförandet av aktiesplit för att revidera aktiens nominella pris. Studiens hypotes lyder därför att det finns ett negativt samband mellan det nominella aktiepriset och ex-dagseffekten, som visats i tidigare studie på den amerikanska börsen NYSE. Studien har genomförts i positivistisk tradition genom statistiska analyser och tester för att klargöra ett eventuellt samband mellan den beroende variabeln ex-dagseffekten och den oberoende variabeln nominella priset. All empirisk data har hämtats från databasen Thomson Reuter Datastream, sammanställts i Excel kalkylblad, analyserats i statistikprogrammet MiniTab och redovisats i två uppsättningar. Studiens resultat visar inget samband mellan det nominella priset och ex-dagseffekten under perioden 2011 till 2015. Nollhypotesen kan inte förkastas och resultaten indikerar försumbar korrelation och förklaringsgrad genom regression. Resultatet är annorlunda från en tidigare studie som konstaterat ett tydligt samband mellan samma variabler på börsen i USA. Det teoretiska bidraget består främst av besvarandet av studiens syfte där det nominella prisets betydelse ter sig annorlunda på den svenska marknaden mot den amerikanska. Det praktiska bidraget från studien ger företagsledare för börsnoterade bolag samt fondbolag och aktörer på den finansiella marknaden en utökad kunskap om rådande förhållanden på marknaden för att förbättra beslutsunderlaget vid eventuella aktiesplittar eller investeringar. Som förslag till fortsatt forskning uppmuntras det att undersöka huruvida det nominella prisets betydelse skiljer sig mellan olika marknader. Förslagsvis kan framtida studier mäta effektiviteten på stockholmsbörsen på dagen för aktiesplit som också i teorin är en mätbar händelse på de finansiella marknaderna under rätt förutsättningar. / The aim of this study is to test for a correlated connection between the nominal stockprice and the price-drop-to-dividend ratio on the Swedish stock market Nasdaq OMX Stockholm. A strong correlated connection would be another motive for company managers to implement a stock split to reduce the nominal stock price. Therefore the hypothesis of the study is that there is a negative correlation between the two variables, just as shown in a recent study on the American stockmarket NYSE. This study has been computed with a positivistic approach through statistical tests and analysis to discover an eventual correlated connection between the dependent variable price-drop-to-dividend ratio and the independent variable nominal price. All empirical data was collected from Thomson Reuter Datastream, compiled in Excel worksheet, analyzed with statistical software MiniTab and presented in two sets of data. The result of this study shows no correlated connection between the nominal stock price and the pricedrop-to-dividend ratio during the period of 2011 to 2015. The null hypothesis can not be rejected and the results of the analysis indicate negligible correlation and coefficient of determination through regression, regardless which sets of data observed. The result is different to a recent study which has shown a significant correlated connection between the same two variables on the American stock market NYSE. The theoretical contribution comprises foremost of answering the aim of the study where the nominal prices impact acts differently on the Swedish stock market compared to the American. Also a presenting of the mean value of price-fall-to-dividend ratio for the period examined is a theoretical contribution. The practical contribution from this study give managers for listed companies along with fund managers and operators on the financial markets an increased knowledge about current influences on the market which improves their ability to make decisions about stock split and future investments. For future studies we suggest to do more research on how the impact of nominal prices differ among markets. Tentatively future research can measure the stockholm market efficiency on the day of stocksplit which according to theory is another measureable event on the financial markets under the right circumstances.

La première rédaction enquête sur la politique de dividende récemment établie sur le marché boursier vietnamien et expérimente les périodes condensées de forte croissance et chute brutale avec une approche en deux étapes. Les résultats de la recherche montrent : (1) Les investisseurs sont d’avantage expropriés dans les entreprises dont la part de détention d’actions des initiés est plus élevée ; (2) Les investisseurs tendent à percevoir le versement de plus faibles dividendes comme un signal relatif à la rentabilité espérée dès lors que l’asymétrie d’information est réduite ; (3) Les investisseurs dans les entreprises contrôlées par l’Etat sont plus enclins à recevoir des dividendes que celles qui ne le sont pas. La seconde rédaction pose que le marché vietnamien des actions est un laboratoire prometteur pour enquêter sur le comportement des cours de marché le jour du Exdividende. Les résultats des recherches suggèrent que les investisseurs du marché boursiervietnamien sont indifférents à l’écart dans l’application de taxe sur les revenus des dividendes. Ils cherchent à capter des dividendes s’ils trouvent des opportunités de profit. Par conséquent, les investisseurs achètent des actions le jour du Cum-dividende et les vendent le Ex-dividende pour exploiter les opportunités de profit générées par le paiement de dividendes. La dernière rédaction examine les effets des droits des actionnaires et des créanciers sur la politique de dividende lorsqueles frais de représentation des actionnaires et des créances tendent à augmenter. Ses découvertes indiquent que les actionnaires et les créanciers sont plus souvent expropriés et l’augmentation des expropriations des créanciers (actionnaires) est plus élevée si les actionnaires (créanciers) sont fortement protégées par la réglementation. / The first essay investigates dividend policy in Vietnamese stock market which is newly established and experiences short booming and crashing periods with a two-step approach. The research findings show: (1) investors are expropriated more in firms with higher insider ownership; (2) Investors tend to receive smaller dividends paid as a signal of expected profitability when information asymmetry is lower; (3) investors in state-controlled firms are more likely to receive dividends than those in non-state-controlled firms. The second essay posits that Vietnamese stock market is a promising laboratory to investigate stock price behavior on ex-dividend day. The research results imply that investors in Vietnamese stock market is indifferent to the difference in tax treatment of capital gains to dividends, they try to capture dividends if they find profit opportunities. Therefore, investors buy stocks on the cum-dividend day and sell them on the exdividend to exploit profit opportunities created by dividend payment. The third essay examines the effects of shareholder rights and creditor rights on dividend policy when agency costs of shareholders and creditors tend to increase. Its findings indicate that are more expropriated and theincrease in the expropriation of creditors (shareholders) is higher if shareholders (creditors) are protected strongly by law.

Aktiemarknaden uppfattas som effektiv då aktiepriset faller i paritet med utdelningen på ex-dagen. Tidigare studier ger belägg för att aktiepriset faller med mindre än utdelningen. Att aktiepriset faller med mindre än utdelningsbeloppet på ex-dagen utgör ex-dagseffekten och innebär en avvikande avkastning för aktier kring ex-dagen. Ex-dagseffektens existens har genom historien undersökts och det råder delade meningar kring dess uppkomst och existens. Skattehypotesen, kortsiktiga handelshypotesen, mikrostrukturhypotesen och dispositions-effekten är fyra olika förklaringar till ex-dagseffektens uppkomst som ligger till grund för denna studie. Hypoteserna analyseras i samband med tidigare utförda studier och sedan dras slutsatsen att skattehypotesen är den mest uppmärksammade förklaringen till ex-dagseffekten. / The stock market is perceived as efficient under the presumption that stock prices falls in parity with the dividends on the ex-dividend day. Earlier researches establish that stock prices rather falls with less than the amount of the dividend. The phenomen that the stock prices falls with less than the dividend constitutes the ex-div effect and implicate an abnormal return on the ex-dividend day. The existence of the ex-div effect has been examined through the history and there are shared opinions about its origin and existence. The tax hypothesis, the short-term trading hypothesis, the microstructure hypothesis and the disposition effect are four different explanations of the ex-div effect that forms the basis of this study. The hypotheses are analyzed in conjunction with earlier researches and the conclusion of the study is that the tax hypothesis is the most common explanation for the ex-div effect.

本文以除權息前後累積異常報酬率為應變數，探討稅額扣抵比率及股權集中度對除權息前後累積異常報酬率的影響。研究對象為民國88年至96年間分配盈餘的國內上市公司，排除行業性質特殊之金融業，以普通最小平方法從事實證模型分析。主要實證結果彙整如下： 1.稅額扣抵比率與除權息前之累積異常報酬率呈顯著正相關，與除權息後之累積異常報酬率呈負相關，但較不顯著。此表示稅額扣抵比率的租稅因素影響在除權息前較為顯著，但在除權息後現象較不顯著。 2.股權集中度與除權息前後之累積異常報酬率的關係均未達統計上顯著水準。產生此實證結果的可能解釋有二：（1）非稅成本的考量；（2）本文以股權集中度衡量可能並未真正捕捉到個人投資人的所得稅率。 3.低稅額扣抵比率類的除權息前累積異常報酬率，較高稅額扣抵比率（基準）類樣本為低的現象，此與預期相符。但在其他加入類別虛擬變數的迴歸結果，並未發現在不同稅額扣抵比率或股權集中度下，會對除權息前後之累積異常報酬率有不同的影響。 4.公司規模及股價淨值比與除權息前後累積異常報酬率均呈顯著正向關係；股利殖利率與除權息前累積異常報酬率呈顯著正向關係，而與除權息後之累積異常報酬率呈顯著負向關係。電子業別與除權息前之累積異常報酬率呈顯著負向關係，而與除權息後之累積異常報酬率呈顯著正向關係。 在圖表的分析中，可看出高稅額扣抵比率或低股權集中度的樣本，其除權息前後累積異常報酬率波動較小，較不受除權息事件的影響。 / The main purpose of this paper is to examine, before and after the ex-dividend day, the impacts of imputation credits and ownership concentration on cumulative abnormal returns(CARs). In this paper , CARs before and after the ex-dividend day are used as the dependent variable. The data are collected from the domestic listed companies which had allocated the earnings from 1999 to 2006. Because of its special characteristics, the financial industry is excluded from the data. In order to analyze the impacts of imputation credits and ownership concentration on CARs , we used the ordinary least squares. The empirical results in this paper are summarized as follows: 1.The imputation credits have a significant positive impact on CARs before the ex-dividend day, but they don’t have a significant negative impact on CARs after the ex-dividend day. This phenomenon implies that the influence of tax factor before the ex-dividend day is more significant than that after the ex-dividend day. 2.The failure of finding a significant relation between ownership concentration and CARs of before and after the ex-dividend day maybe due to two reasons. Frist, investors may not take tax factor into account when they invest the stock. Second, the proxy variable for ownership concentration of this study may not fully capture the marginal income rate of individuals. 3.CARs before the ex-dividend day in listed company with lower imputation credit are lower than that in listed company with higher imputation credit, the empirical result matchs general intuition. But other regressions with dummy variables regarding the degree of the imputation credit and ownership concentration don’t find significant relation among the imputation credit, ownership concentration and CARs before and after the ex-dividend day. 4.The size of companies and the ratio of market price to their book value have a significant positive impact on CARs before and after the ex-dividend day. Dividend yield has a significant positive impact on CARs before the ex-dividend day, but a negative impact on CARs after the ex-dividend day. A dummy variable standing for electronic industry has a significant negative impact on CARs before the ex-dividend day, but positive impact on CARs after the ex-dividend day. In the analysis of diagrams, we find CARs before and after the ex-dividend day fluctuate less for companies with higher imputed credit or lower ownership concentration.

På en effektiv marknad ska förändringen i aktiepriset under ex-dagen vara sådan att en investerare är indifferent till att genomföra en transaktion inklusive eller exklusive utdelning. Trots det pekar flertalet empiriska studier på att så inte är fallet. I denna studie använder vi prisfallskvoten enligt Elton och Gruber (1970) för att undersöka kursbildning kring ex-dagen på Stockholmsbörsen åren 2013-16 samt om det finns skillnader i priskorrigering mellan olika grupper av aktier. Vi finner att aktierna på Stockholmsbörsen i genomsnitt föll med 76 % av utdelningsbeloppet och således har det funnits en ex-dagseffekt. Vidare visar studien att ex-dagseffekten är större i bolag med låga utdelningsbelopp och låg direktavkastning. Resultaten i studien visar även en signifikant positiv avvikelseavkastning under ex-dagen men avkastningen anses vara för liten för att motivera systematisk handel.